The present invention relates in general to an image display device of the type which includes electron beam sources having electron sources (cathodes) which emit electrons and phosphors, which are excited upon radiation by electron beams that are emitted from the electron sources toward anodes; and, more particularly, the invention relates to an image display device of the type described, which includes an improved voltage supply means that supplies a high voltage to the anodes.
As a display device which exhibits a high brightness and high definition, color cathode ray tubes have been widely used for many years. However, along with the recent desire for images of higher quality in information processing equipment or television broadcasting, the demand for planar displays (panel displays) which are light in weight and require a small space, while exhibiting high brightness and high definition, has been increasing. As typical examples, liquid crystal display devices, plasma display devices and the like have been put into practice.
More, particularly, as display devices which can realize a higher brightness, it is expected that various kinds of panel-type display devices, including a display device which utilizes an emission of electrons from electron sources into a vacuum, referred to as “an electron emission type display device”, or “a field emission type display device”, and an organic EL display, which is characterized by low power consumption will be commercialized.
Among such panel type display devices, such as the above-mentioned field emission type display device, particularly, a display device having an electron emission structure which was invented by C. A. Spindt et al, a display device having an electron emission structure of a metal-insulator-metal (MIM) type, a display device having an electron emission structure which utilizes an electron emission phenomenon based on a quantum theory tunneling effect (also referred to as a “surface conduction type electron source), and a display device which utilizes an electron emission phenomenon having a diamond film, a graphite film or carbon nanotubes have been proposed.
Among such panel type display devices, the field emission type display device, as shown in FIG. 9 herein, which is a developed perspective view, is constituted such that spacers SPC, which are arranged at given intervals, and a sealing frame MFL are interposed between a face panel PN2, which includes an anode and a phosphor on an inner surface thereof, and a back panel PN1 which has field emission type cathodes and control electrodes formed therein; and, these panels have portions thereof disposed around the display region that are laminated to each other and sealed to each other at the sealing frame MFL. Thereafter, the pressure inside a sealed space defined between the two panels is reduced by evacuating to a level that is lower than ambient pressure or is maintained in a vacuum condition. Then, electron beams which are emitted from the cathodes, while a high voltage is supplied to the anode, are accelerated by control electrodes MG, thus efficiently causing a phosphor screen to emit light.
In a field emission type display device having such a constitution, to supply a high voltage to the anode, as shown in FIG. 10(a) and FIG. 10(b), a method has been adopted in which a portion of the anode ADE is extended out to an end portion of the face panel PN2 in the same pattern and, at the same time, projects to the outside of the sealing frame MFL, thus forming an anode terminal ADE-T. Here, the illustration of various types of electrodes and the like, which are formed on the back panel PN1, has been omitted in the drawing.
According to such a constitution, although an electrical connection which serves to supply a the high voltage to the anode terminal ADE-T from the outside is ensured, the constitution requires a structure in which the anode-terminal ADE-T is exposed to the atmosphere, and, hence, it is difficult to ensure the desired dielectric strength property thereof. Further, the adhesion and fixing of the sealing frame MFL and the face panel PN2, on which the anode ADE is formed, are performed using a low-melting-point glass material (frit glass) or the like, and, hence, it is difficult to also ensure the desired dielectric strength characteristics.
Further, as another voltage supply means, for example, Japanese Laid-open patent publication Hei10(1998)-31433 discloses a field emission type display device having the following connection means. That is, an anode lead which has one end thereof connected by pressing to an anode terminal of the anode formed on an inner surface of the face panel has the other end thereof pulled out to the outside after hermetically penetrating a getter chamber. Further, in Japanese Laid-open patent publication Hei10(1998)-326581 discloses a field emission type display device having the following constitution. That is, an anode lead which has one end thereof connected to a lead line of an anode, which is formed on an inner surface of the face panel, has the other end thereof pulled out to the outside after being allowed to hermetically pass through a back panel.
Further, Japanese Laid-open patent publication 2000-260359 and Japanese Laid-open patent publication 2003-92075 disclose a field emission type display device having the following constitution. That is, an anode lead, which has one end thereof connected to an anode terminal of the anode formed on an inner surface of the face panel, is pulled out to the outside after being allowed to pass through the inside of a through opening formed in a back panel, which through opening is formed at a corner thereof by way of an insulating member. Further, Japanese Laid-open patent publication 2000-311636 discloses a field emission type display device having the following constitution. That is, an anode lead, which has one end thereof connected to an anode terminal of the anode formed on an inner surface of the face panel, is pulled out to the outside after being allowed to pass through the inside of an insulating body, which is formed in a through hole of the back panel.